       Replace in an elegant way

• To: mathgroup at smc.vnet.net
• Subject: [mg122865] Replace in an elegant way
• From: Mirko <dashiell at web.de>
• Date: Sun, 13 Nov 2011 04:43:13 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```Hi all,
I have following equation:

((1 + theta[m])^2)/(1 - m) - lambda*((theta[m] + ((lambda + m - lambda*m)*(1 + theta[m])*(1 + theta[m] - lambda*theta[m]))/(1 - m) +
(m*Derivative[theta][m])/lambda))

I want to replace all m that are not an argument of theta[m] or the Derivative. However, if I use
/., it replaces all m. If I use Replace[expr,m->qq] it doesn't replace anything. (qq is the one I want to replace with). If I specify any level, it doesn't change anything, unless I use -1, but then I replace everything.

Do you know how I solve this problem?
Right now I use:
//. Derivative[y_][theta][m] -> Derivative[y][theta][dd] //.
theta[m] -> theta[dd] /. m -> qq //.
Derivative[y_][theta][dd] -> Derivative[y][theta][m] //.
theta[dd] -> theta[m]

but this is not elegant at all (and takes slightly longer).

```

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